Time is a valuable commodity for humans. We like our news up to the minute and our technology up-to-date. But when it comes to some temporal boundaries scientists are still trying to figure out what's up.
There is no doubt that humanity is impacting the planet, but geologists are facing a problem. Has the footprint of our species made so much of an imprint on the planet that it's worth declaring the start of an entirely new geologic time period?
Some think so, advocating for the creation of a new epoch of time called the 'Anthropocene,' or the 'age of man', to indicate our domination over the earth. But how can we tell? Usually geologists decide that a new epoch or era has started once they figure out that something new has appeared in the rock record at a particular time. It could be dust from the comet that killed the dinosaurs, ash from a particularly epic volcanic eruption, or fossils that appear or disappear in bursts of evolution or mass extinctions. Up until now, we've been content members of the Holocene, a geologic epoch that started with the end of the last ice age.
A study published this week in Nature suggests that the starting line of the Anthropocene should be drawn in 1610, which is earlier than previous suggestions.
The authors argue that the environmental changes that occurred during the "New-Old World Collision" (when Europeans began traveling to the Americas in earnest) were large enough and widespread enough that they mark a dramatic shift in the geologic record. Those changes include the appearance of New World species in the Old World (and the reverse) as crops and people travelled across the sea--essentially the start of globalization. The authors chose the year 1610 because it was also the year of the last low point of carbon dioxide found in ice cores--an easily recognizable dividing line, so long as the ice caps hold out.
But the 1610 date faces some steep competition. One of the first suggestions for a starting date was the year 1800, when the Industrial Revolution began in Europe. But we humans have been polluting on a large scale for a really long time, leaving the evidence in the rock record spread out and disjointed. Another potential date suggested in the Nature paper is 1964, when nuclear testing (and radioactive material) reached a peak, leaving traces of nuclear material around the globe, and potentially in the geologic record.
The final decision will be made next year by the Anthropocene Working Group a group of experts from around the world, who are tasked with determining whether the term Anthropocene is "(a) scientifically justified (i.e. the 'geological signal' in rock strata must be sufficiently widespread, clear and distinctive) and (b) useful as a formal term to the scientific community."